Abstract: Coal and char are essential energy sources for the process industry. Insightful understanding of those molecules is useful to explore reactivities of coal and char. Therefore, coal and char molecular structures were investigated at atomic level using Materials Studio 7.0 software. Firstly, coal and char initial structures were constructed based on reported literatures. Secondly, those structures were improved by molecular mechanics, where functional group fragments were added to satisfy the property of coal or char. Then, the subsequent structures were optimized by annealing dynamics simulation to adjust density and elementary composition. Finally, the potential energies of coal and char were calculated using energy minimization method. It was pointed out that the estimated densities and elementary composition were agreements with the published literatures, which indicated that those structures were valid and reasonable. From the simulated results, it was shown that the Coulomb energy and van der Waals energy played a much more important role than other energies during the stabilizing molecular construction process. Thus, it was inferred that the weak bond was predominant in the thermal processing of coal or char. In addition, this work demonstrated that the molecular simulation technology was meaningful to construct the complex macromolecular structure.
Abstract: Lignite samples with different ash contents and mineral composition were prepared by dry separation and acid washing. A drop tube reactor and thermogravimetric analyzer were used to study effect of inherent minerals on CO2 gasification reaction of lignite at 1 000-1 200 ℃. The results show that the inherent minerals have positive effects on gasification, which are temperature sensitive. At lower gasification temperature (1 000 ℃) the inherent minerals can improve carbon conversion indirectly by obstructing the carbon structure order of nascent char. At higher temperatures (1 100-1 200 ℃)the inherent minerals can improve carbon conversion by catalyzing nascent char gasification directly. The alkaline index is not suitable for characterizing role of the inherent minerals of lignite in this case. Ca leads to the difference in catalytic activity of the inherent minerals where the most active form is carboxylate. Various catalytic mechanisms are the root cause of different catalytic activity of Ca in different chemical forms. Ca in the form of carboxylate can reduce the activation energy of coal/char gasification reaction, while CaO only promotes the apparent frequency factor.
Abstract: Raw biomass and its de-potassium sample washed by water were pyrolyzed in a fixed bed reactor under pure N2 and CO-rich atmosphere at different temperatures. The obtained biomass chars were characterized by Fourier transform infrared spectroscopy (FT-IR), surface area analyzer, inductively coupled plasma emission spectroscopy and polarizing microscope. The yields of char, functional groups and other physicochemical structure were also studied and their evolution behaviors were examined. The results show that below 750 ℃, the BET surface areas and the amounts of alkyl and aliphatic functional groups in the chars derived from raw biomass are higher than those of de-potassium ones, but the char yields and the amounts of aromatic functional groups in the chars of raw biomass are lower than that of de-potassium samples. As to the effect of CO atmosphere, the yields of char and the amounts of all functional group in the chars derived from CO-rich atmosphere are less than that of N2 atmosphere, But the surface areas is higher than that of N2 atmosphere. Above 750 ℃, both potassium and CO can help to increase the char yields but decrease the amount of functional group and BET surface areas. In addition, the minerals are highly scattered and theirs amount on the surface of chars (raw biomass char, N2 atmosphere) is less when the pyrolysis temperature is lower than 750 ℃; while above 750 ℃, those are higher and the clusters of fusion mineral components increases with increasing pyrolysis temperature. As for the graphitization degree of biomass chars, it increases with increasing pyrolysis temperature but poor graphitization was obtained when the pyrolysis temperature is lower than 750 ℃. Moreover, CO can help to increase while K decreases the graphitization degree above 750 ℃.
Abstract: Effect of extraction temperature (160, 180 and 200 ℃) on depolymerization characteristics of ethanol organosolv lignin (EOL) was investigated with a micro autoclave reactor. Three different EOLs (EOL-160, EOL-180 and EOL-200) were prepared by controlling extraction temperature, and their properties including functional groups, molecular weight distribution and thermogravimetric properties were analyzed by infrared spectroscopy (FT-IR), gel permeation chromatography (GPC) and thermogravimetric analysis (TG). The liquid and solid products obtaining from EOLs depolymerized in supercritical ethanol were analyzed by gas chromatography/mass spectrometry (GC/MS) and FT-IR, respectively. The results show that the main phenolic compound product for EOL-160, EOL-180 and EOL-200 depolymerized in supercritical ethanol were paraethyl phenol, 2,6-dimethoxy phenol and 4-hydroxy-3-methoxy-benzoate, respectively.
Abstract: This work presents a synthesis of bimetallic NiMo and NiW modified ZSM-5/MCM-41 composites and their heterogeneous catalytic conversion of crude palm oil (CPO) to biofuels. The ZSM-5/MCM-41 composites were synthesized through a self-assembly of cetyltrimethylammonium bromide (CTAB) surfactant with silica-alumina from ZSM-5 zeolite, prepared from natural kaolin by the hydrothermal technique. Subsequently, the synthesized composites were deposited with bimetallic NiMo and NiW by impregnation method. The obtained catalysts presented a micro-mesoporous structure, confirmed by XRD, SEM, TEM, EDX, NH3-TPD, XRF and N2 adsorption-desorption measurements. The results of CPO conversion demonstrate that the catalytic activity of the synthesized catalysts decreases in the series of NiMo-ZSM-5/MCM-41 > NiW-ZSM-5/MCM-41 > Ni-ZSM-5/MCM-41 > Mo-ZSM-5/MCM-41 > W-ZSM-5/MCM-41 > NiMo-ZSM-5 > NiW-ZSM-5 > ZSM-5/MCM-41 > ZSM-5 > MCM-41. It was found that the bimetallic NiMo-and NiW-ZSM-5/MCM-41 catalysts give higher yields of liquid hydrocarbons than other catalysts at a given conversion. Types of hydrocarbon in liquid products, identified by simulated distillation gas chromatography-flame ionization detector (SimDis GC-FID), are gasoline (150-200 ℃; C5-12), kerosene (250-300 ℃; C5-20) and diesel (350 ℃; C7-20). Moreover, the conversion of CPO to biofuel products using the NiMo-and NiW-ZSM-5/MCM-41 catalysts offers no statistically significant difference (P > 0.05) at 95% confidence level, evaluated by SPSS analysis.
Abstract: A series of NiCoB amorphous alloy catalysts were prepared by chemical reduction method in different single and mixed solvent systems and their performance for liquid phase hydrogenation of furfural (FUR) was evaluated. The catalysts were also characterized by N2 adsorption-desorption, ICP, FE-SEM, HRTEM, XRD and XPS. The results showed that the surface tension, viscosity, polarity and solubility parameter of preparation solvent had important effects on the composition, morphology, structure and the catalytic properties of FUR hydrogenation of the NiCoB amorphous alloy catalyst. The NiCoB-MEG catalyst prepared by the mixed solvent of methanol/ethylene glycol (MEG, volume ratio of 1:1) showed the optimum liquid phase hydrogenation performance of FUR to furfuryl alcohol (FA) with a FUR conversion of 96.4% and a FA selectivity of 83.49%. It can be due to the improvement of dispersion and reduction of metallic components by the synergistic effect between methanol and ethylene glycol.
Abstract: HZSM-5 zeolite was treated by sodium hydroxide solution, and then characterized by XRD, SEM, BET and Py-FTIR, respectively. Physical and chemical properties and composition analysis was applied to the organic phase of bio-oils. Thermogravimetric analysis was performed on three deactivated catalysts after using for 120 min and the peak area of char was calculated. The results show that the alkali-treated HZSM-5 catalyst retains typical MFI topology structure and forms a certain number of mesoporous. At the same time, the bio-oil organic phase made with modified HZSM-5 (after 1 h treatment) achieves a higher yield rate and better physical properties. The content of hydrocarbons increases significantly to 37.67% mainly with the increase of mononuclear aromatics. In addition, modified HZSM-5 catalyst (after 1 h treatment) has a better effect on the removal of acid, aldehyde and ketone contained in the bio-oil organic phase, which improves stability of the bio-oil with calorific value of 35.32 MJ/kg. The amount of coke in the HZSM-5 zeolite after 1 h alkali treatment obviously decreases.
Abstract: Polyoxymethylene dimethyl ethers (H3CO(CH2O)nCH3, PODEn or DMMn, n ≥ 2) with unique physical and chemical properties are a potential additive for diesel fuels, which can effectively enhance the combustion efficiency and reduce the emission of pollutants. In this work, a series of pure PODEn components (n=2-5) were synthesized from methylal and trioxymethylene and obtained with high purity through collaborative separation; their structure and properties were characterized by NMR, FT-IR, Raman, and DFT calculation and a detailed assignment of the expressions in the spectrogram to the various groups was performed. The density and viscosity of PODEn were measured at 298.15-323.15 K. The results indicate that the density and viscosity of PODEn decrease gradually with the increase of temperature. Meanwhile, with the increase in the number of -CH2O-units (n) from 2 to 5, the density, viscosity, flash point, pour point, and the heat of fusion and solidification of PODEn are all increased. These results are valuable for the practical synthesis and application of PODEn.
Abstract: To enhance the performance of nickel-based catalysts in the reforming of CH4 with CO2 and alleviate the coke deposition, a series of NiCo/MgO catalysts were prepared by different methods, viz., deposition-precipitation (DP), co-precipitation method (CP) and co-impregnation (CI); the influence of preparation method on the structure and performance of NiCo/MgO catalyst was then investigated. The results show that during the deposition-precipitation process, CO(NH2)2 as the precipitant could created an alkaline atmosphere for the complete hydrolysis of Ni2+ and Co2+ ions, leading to a relatively fast nucleation and growth of active species; however, oversaturation may occur during the co-precipitation process with NaOH and Na2CO3 as the precipitants. In comparison with the catalysts prepared by CP and CI, the NiCo/MgO-DP catalyst is provided with superior reduction capacity, smaller particle size (9.7 nm), higher Ni/Co dispersion (10.4%) and larger specific surface area (68.1 m2/g) and then exhibits better resistance to coke deposition. Over the DP catalyst, the conversions of CH4 and CO2 at 800 ℃ reach 88% and 92%, respectively, much higher than those over the CP and CI catalysts; moreover, the DP catalyst also gives much higher yield of H2 and CO as well as better stability for methane reforming with CO2.
Abstract: Mo/ZrO2 and Mo/Al2O3 catalysts with a MoO3 loading of 5% were prepared by incipient wetness impregnation method; the effect of support on the performance of Mo-based catalysts in methanation was then investigated in three different feeds. The results indicate that ZrO2 as a support can promote the methanation and water-gas shift (WGS) reaction. ZrO2 is beneficial to the sulfuration and reduction of MoO3. The Mo sulfidation degree and the content of Mo4+ on Mo/ZrO2 are higher than that on Mo/Al2O3. Besides, the curved MoS2 basal plane on Mo/ZrO2 can provide the active sites for methanation and WGS, which is effective to enhance the performance of Mo-based catalysts in methanation.
Abstract: The UZM-9 zeolite was synthesized in 48 h via a seed-assisted method, in which TEAOH and TMAOH were used as organic structure directing agent (OSDA) while acid-treated UZM-9 zeolites were employed as seeds. The textural properties and hydrophobicity of the as synthesized UZM-9 zeolites and their adsorption properties for CO2/CH4/N2 were characterized by XRD, physical adsorption, SEM, ICP and TG, respectively. The results show that UZM-9 zeolites can be obtained in 2 d with the Si/Al atomic ratio up to 3 and the yield up to 65%. At 298 K and 1atm, the capacity and adsorption heat of CO2 are 5 mmol/g and 34 kJ/mol, and the selectivity of CO2/CH4, CO2/N2 and CH4/N2 are 100, 240 and 2.4 respectively. These results reveal that the as synthesized UZM-9 zeolites have good performances for carbon capture and possess considerable water resistance.
Abstract: Utilizing microbial fuel cells (MFCs) is a promising technology for energy-efficient domestic wastewater treatment, but it still faces practical barriers such as low power generation. In this study, the LaMnO3 perovskite-type oxide nanoparticles and nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite (the cathode and anode catalysts, respectively) have been prepared and used to enhance power density of MFC. The prepared La-based perovskite oxide catalysts were characterized by X-ray diffraction (XRD) and scanning electron microscopies (SEM). The electrocatalytic properties of the prepared catalysts were investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and Tafel plot at ambient temperature. Results show the exchange current densities of LaMnO3/carbon cloth cathode and NCP nanocomposite/carbon cloth anode were 1.68 and 7 times more compared to carbon cloth cathode, respectively. In comparison to the bare carbon cloth anode, the MFC with the modified electrodes shows 11 times more enhancement in power density output which according to electrochemical results, it can be due to the enhancement of the electron transfer capability. These cathodic and anodic catalysts were examined in batch and semi-continuous modes to provide conditions close to industrial conditions. This study suggests that utilizing these low cost catalysts has promising potential for wastewater treatment in MFC with high power generation and good COD removal efficiency.
Abstract: A series of solid amine adsorbents were prepared by using three different preparation methods with ion exchange resin (D001) as carrier and with tetraethylenepentamine (TEPA) as modifier. The sorbents were characterized by nitrogen adsorption/desorption, Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) techniques. The effects of TEPA loadings, adsorption temperatures, influent gas flow rates and CO2 partial pressure on the CO2 adsorption capacity in a fixed bed reactor were investigated. The results show that the solid amine adsorbent prepared by the coordination method has a better dispersibility and stability, and the maximum CO2 adsorption capacity is 4 mmol/g when the TEPA loading is 40%, the adsorption temperature is 65 ℃ and the influent gas flow rate is 40 mL/min. The amount of CO2 adsorption only decreases by 3.98% and remains almost unchanged after 10 cycles of desorption and desorption. The study of thermodynamics and kinetics indicates that the adsorption mechanism is dominated by both chemical and physical adsorption.
Abstract: In order to study the influence of desulfurization wastewater evaporation (DWE) on the ESP and the desulfurization performance, an experimental setup with DWE and the coal-fired thermal system was established. The removal of PM2.5 and SO3 from coal combustion with DWE and the evolution of fine particle size and PM2.5 and SO3 concentration at ESP outlet were investigated. Also, the mechanism of PM2.5 and SO3 removal was analyzed. The results show that DWE can increase the average size of particles from 0.1 μm to 1.1 μm. Compared SEM image before DWE with that after DWE, the particles reuniting and floc formation between particles are clearly observed. The ESP efficiency is increased by 5%; the removal efficiency of PM2.5 in number concentration is increased by 25% at the ESP outlet; and the removal efficiency of SO3 by ESP is 60%-80%. The SO3 concentration in flue gas has an effect on PM2.5 and SO3 removal by ESP. However, the DWE has no effect on the desulfurization efficiency and the pH value of the desulfurization slurry.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
